Field of the Invention
The present invention relates to an assembly for tamping ballast underneath successive ties of a track, adjacent ones of the ties defining cribs therebetween, in which the ballast tamping assembly comprises two tamping tool carriers arranged successively in a longitudinal direction, a pair of tamping picks mounted on each tamping tool carrier, one of the tamping picks of each pair being arranged at a respective end of the assembly in the longitudinal direction for immersion in a respective one of the cribs, another one of the tamping picks of each pair being one of twin tamping picks, the twin tamping picks being arranged for immersion in cribs adjacent the respective cribs for tamping ballast underneath two adjacent ties, and each tamping pick being pivotal about a horizontal axis extending transversely to the track, the horizontal axes extending parallel to each other and the longitudinal direction extending perpendicularly to the horizontal axes. Reciprocating drives are provided for pivoting the tamping picks, and drives are provided for vibrating the tamping picks, a respective one of the reciprocating drives connecting each tamping pick to a respective one of the vibrating drives. Furthermore, drives are provided for vertically adjusting the tamping tool carriers independently of each other.
Such a ballast tamping assembly has been disclosed in U.S. Pat. No. 5,133,263. The two tamping tool carriers are mounted on a carrier frame of a machine movable on a track and may be vertically adjusted together or separately for immersion of the tamping picks in the ballast. When the tamping tool carriers are vertically adjusted together, a track section comprising three successively arranged ties may be tamped at one time, the tamping picks at the ends of the assembly and one of the tamping picks of the twin tamping picks mounted on the same tamping tool carrier tamping the two outer ones of the three ties while the other tamping picks of the twin tamping picks tamps the center tie. In addition, it is possible to use the machine for tamping a single tie by operating only one of the tamping tool carriers, for example if the ties are irregularly spaced or if some obstacle is encountered.
DE-OS 24 26 841 also discloses a ballast tamping assembly with two tamping tool carriers, each having three tamping picks to tamp either three ties simultaneously or only one tie at a time.
JP 54-45011 describes an arrangement of three ballast tamping tool carriers arranged successively in a longitudinal direction and whose spacing in this direction may be adjusted. Each tamping tool carrier is independently vertically adjustable and has tamping picks for tamping single ties so that it is possible to tamp one, two or three ties at the same time.
The mobile track tamping machine disclosed in U.S. Pat. No. 4,094,250 has two independently vertically adjustable tamping tool carriers spaced from each other in the longitudinal direction. Two twin tamping picks are mounted on each tamping tool carrier and they are so spaced from each other in the longitudinal direction that they may be immersed in adjacent cribs, the tamping picks of each one of the twin tamping picks being spread apart from each other for tamping ballast underneath adjacent ties. In this way, when the tamping picks of both tamping tool carriers are simultaneously operated, the ballast underneath three adjacent ties may be fully tamped as well as half of the ballast underneath the two ties adjacent the group of three ties.
U.S. Pat. No. 3,494,297 discloses tamping of four adjacent track ties without describing the ballast tamping assembly in detail.
It is the primary object of this invention to provide a ballast tamping assembly of this general type which has an enhanced operating capacity and affords additional operational possibilities.
This object is accomplished with an assembly for tamping ballast underneath successive ties of a track, adjacent ones of the ties defining cribs therebetween, in which the ballast tamping assembly comprises two tamping tool carriers arranged successively in a longitudinal direction, a pair of tamping picks mounted on each tamping tool carrier, one of the tamping picks of each pair being arranged at a respective end of the assembly in the longitudinal direction for immersion in a respective one of the cribs, and another one of the tamping picks of each pair being one of twin tamping picks, the twin stamping picks being arranged for immersion in cribs adjacent the respective cribs for tamping ballast underneath two adjacent ties. According to the invention, a third tamping tool carrier is arranged between the two successively arranged tamping tool carriers, further twin tamping picks being mounted on the third tamping tool carrier, the further twin tamping picks being arranged for immersion in a center crib. Each tamping pick is pivotal about a horizontal axis extending transversely to the track, the horizontal axes extending parallel to each other and the longitudinal direction extending perpendicularly to the horizontal axes, reciprocating drives pivot the tamping picks, and a respective one of the reciprocating drives connects each tamping pick to a drive for vibrating the tamping picks. Drives are provided for vertically adjusting the tamping tool carriers independently of each other.
Such a ballast tamping assembly has a substantially enhanced efficiency and enables the tamping capacity of the machine to be increased since the simultaneous operation of the tamping picks of all three tamping tool carriers fully tamps four ties at once. Compared to conventional machines, this provides an increase of the tamping capacity by one third. At the same time, tamping four ties at the same time effects the uniform quality of the ballast tamping favorably since the simultaneous tamping of four ties better assures such a tamping quality. In addition to the improved economy of this machine, a greater variety of its use can be obtained with respect to the number of ties that may be tamped at the same time. The machine can be used for simultaneously tamping one, two or four ties, being adjustable to select the mode of use according to the prevailing track conditions, for example the spacing between the ties and/or the presence of obstacles. If desired, only every other tie may be tamped or only the two ties at the ends of a group of four adjacent ties.